Sulfamethoxazole API CAS 723-46-6 | ≥98% Sulfonamide Antibiotic Manufacturer China

Key Selling Points

✓ Classic Sulfonamide Antibiotic - DHPS Competitive Inhibitor (PABA Antagonist)

✓ Gold-Standard Partner for Trimethoprim - Co-Trimoxazole (5:1 Ratio, WHO Essential Medicine)

✓ Sequential Folate Pathway Blockade With TMP - Bactericidal Synergy (vs Bacteriostatic Alone)

✓ Broad Spectrum - Gram-Positive & Gram-Negative incl. Pneumocystis jirovecii

✓ Long Half-Life (10–12 hr) - BID Dosing, Good Tissue Distribution ✓ Human & Veterinary API - UTI, Respiratory, PJP Prophylaxis, Skin Infections

What Is Sulfamethoxazole Powder?

Sulfamethoxazole Powder (SMX/SMZ) is a classic sulfonamide antibacterial, chemically 4-amino-N-(5-methyl-3-isoxazolyl)benzenesulfonamide, introduced in the 1960s. It is best known as the sulfonamide component of co-trimoxazole - the 5:1 fixed combination with trimethoprim (TMP), listed on the WHO Model List of Essential Medicines.

It is used (primarily as co-trimoxazole) for urinary tract infections, respiratory infections, traveler's diarrhea, and notably the prophylaxis and treatment of Pneumocystis jirovecii pneumonia (PJP), toxoplasmosis and nocardiosis. In veterinary practice it is used in dogs and cats for UTI, skin, respiratory and prostate infections. Alone bacteriostatic; with TMP, bactericidal via sequential folate blockade. Half-life ~10–12 hours (BID dosing), good tissue distribution. Adverse effects include hypersensitivity (up to SJS/TEN), crystalluria/renal injury, hematologic effects, hyperkalemia and hemolysis in G6PD deficiency - use with adequate hydration and monitoring.

How Does Sulfamethoxazole Powder Work?

Sulfamethoxazole Powder competitively inhibits dihydropteroate synthase (DHPS), blocking para-aminobenzoic acid (PABA) utilization and halting de novo folic acid synthesis in susceptible bacteria - which must synthesize folate, unlike mammalian cells that absorb it from diet. Alone, this effect is bacteriostatic.

Its defining clinical feature is synergy with trimethoprim (TMP): TMP inhibits dihydrofolate reductase (DHFR) at the next pathway step, so together they impose a sequential folate blockade that converts bacteriostasis into bactericidal activity and slows resistance. The 5:1 co-trimoxazole combination is active against Gram-positive (Streptococcus, Staphylococcus, Listeria, Nocardia) and Gram-negative (E. coli, Klebsiella, Proteus, Salmonella, Shigella) organisms, plus Pneumocystis jirovecii and Toxoplasma gondii. Excretion is renal; half-life is 10–12 hours (BID dosing). Adequate hydration is required to prevent crystalluria, and use with caution in renal impairment.

What Are the Applications of Sulfamethoxazole Powder?

Urinary Tract Infections: Treatment of susceptible E. coli and other Gram-negative uropathogens in humans, dogs and cats.
Respiratory Tract Infections: Acute exacerbations of chronic bronchitis, sinusitis and pneumonia caused by susceptible organisms.
Pneumocystis jirovecii Pneumonia (PJP): Prophylaxis and treatment in immunocompromised patients (HIV, transplant, immunosuppressive therapy) - the gold-standard indication for co-trimoxazole.
Gastrointestinal Infections: Traveler's diarrhea (ETEC), shigellosis and other susceptible bacterial enteritides.
Veterinary Use: Canine and feline urinary tract, skin, soft tissue, respiratory and prostate infections caused by susceptible bacteria; used as co-trimoxazole or potentiated sulfonamide formulations.

What Is the Difference Between Sulfachloridazine Sodium and Sulfachlorpyrazine Sodium?

Feature	Sulfamethoxazole	Sulfadiazine
CAS	723-46-6	68-35-9
Heterocycle	5-Methylisoxazole	Pyrimidine
Molecular Weight	253.28	250.28
Half-Life	10–12 hours (intermediate)	8–12 hours (short-intermediate)
Primary Partner	Trimethoprim (co-trimoxazole)	Pyrimethamine (toxoplasmosis) / Silver (burns)
PJP Activity	Yes (gold standard)	No
CSF Penetration	Moderate	Excellent
Water Solubility	Practically insoluble	Slightly soluble
Typical Use	UTI, respiratory, PJP	Toxoplasmosis, burns (silver), meningitis

How Does Sulfamethoxazole Compare With Other Sulfonamides?

Feature	Sulfamethoxazole	Sulfadimidine	Sulfamonomethoxine	Sulfachlorpyridazine
CAS	723-46-6	57-68-1	1220-83-3	80-32-0
Half-Life	10–12 hr	6–12 hr	24–36 hr (long-acting)	Short
Primary Use	Human/vet broad (co-trimoxazole)	Veterinary broad	Veterinary (long-acting)	Veterinary (calf E. coli)
TMP Combination	Standard (5:1)	Common	Common	Common
PJP Activity	Yes	No	No	No
Human Use	Extensive	Limited	Rare	Rare
Crystalluria Risk	Moderate	High	Lower	Moderate

How Is Sulfamethoxazole Powder Manufactured?

Sulfamethoxazole Powder is manufactured through chemical synthesis involving acetylation of sulfanilamide, coupling with a 3-amino-5-methylisoxazole intermediate, deprotection and purification.

Raw Material QC → Sulfanilamide Acetylation → 3-Amino-5-methylisoxazole Intermediate → Condensation / Coupling → Deprotection (Deacetylation) → Crude Sulfamethoxazole → Purification (Recrystallization from Ethanol/Water) → Drying → Milling → Final QC → Packaging

HDM BIO controls key coupling, deprotection and crystallization parameters to maintain consistent purity and batch quality.

Quality Specifications

Test Item	Standard	Typical Result
Appearance	White to off-white powder	Consistent
Assay (HPLC)	≥98.0%	99.0%
Identity (IR)	Conforms to reference standard	Confirmed
Melting Point	166–172°C	169°C
Loss on Drying	≤0.5%	0.2%
Residue on Ignition	≤0.1%	Compliant
Heavy Metals	≤10 ppm	Compliant
Arsenic	≤2 ppm	Compliant
Related Substances	Within specification	Pass
Residual Solvents	Within specification	Pass
Sulfated Ash	≤0.1%	Compliant

What Quality Control Tests Are Performed for Sulfamethoxazole Powder?

Each batch undergoes multi-step quality control before release to verify identity, purity and physical properties.

Raw Material QC → In-Process Control → HPLC Assay → IR Identity Verification → Melting Point Determination → Related Substances (HPLC) → Loss on Drying → Heavy Metals → Arsenic → Residue on Ignition → Sulfated Ash → Residual Solvents → Final Batch Release

Key evaluations include identification via infrared (IR) spectroscopy, HPLC active content assay, melting point determination, related substances analysis, loss on drying, heavy metal and arsenic limits, residue on ignition, sulfated ash and residual solvent testing. Every commercial batch is supported by a batch-specific COA and relevant analytical documentation for incoming QC and supplier qualification.

What Factors Affect Sulfamethoxazole Powder Bulk Price?

Sulfamethoxazole Powder bulk pricing is driven by several key factors:

Synthesis Costs: Multi-step chemical synthesis including sulfanilamide acetylation, isoxazole coupling and deprotection directly influences manufacturing expenses.
Purity & Grade: Higher purity (≥99%) and pharmaceutical-grade (USP/EP) batches command premiums over standard grade.
Regulatory Compliance & Certification: GMP-standard API batches with DMF/CEP and consistent COA demand a higher price.
Order Volume: Large-scale pharmaceutical contracts receive steeper per-kilogram discounts than small-batch orders.
Logistics & Geography: Light-protected packaging requirements and customs compliance add to the landed cost.

Contact HDM BIO for a current quotation and volume-based pricing.

Why Choose HDM BIO as Your Sulfamethoxazole Powder Supplier?

High-purity (≥98% / typical 99%) classic sulfonamide with proven co-trimoxazole formulation compatibility
Gold-standard TMP partner - 5:1 ratio co-trimoxazole, WHO Essential Medicine
Broad-spectrum activity including PJP prophylaxis and UTI
GMP-aligned production, ISO & HACCP certified quality system
Full batch traceability and complete documentation (COA, MSDS, HPLC)
Flexible supply: kilogram samples to ton-level bulk orders
Global export to 70+ countries with full customs support

Bulk Packaging, Shipping & Storage

Packaging: Foil bags for samples and moisture-proof fiber drums for bulk orders.
Custom Packaging: OEM labeling available.
Shipping Documents: COA, MSDS/SDS, commercial invoice, packing list and customs documentation available according to order requirements.
Storage: Store tightly sealed in a cool, dry, light-protected environment. Shelf life: 24 months.
Handling: For veterinary raw material use only; not for direct clinical administration.

Frequently Asked Questions About Sulfamethoxazole Powder

Q1: What is Sulfamethoxazole Powder?

A: A classic sulfonamide antibacterial (SMX/SMZ), best known as the sulfonamide component of co-trimoxazole (with trimethoprim), used for UTI, respiratory infections and PJP prophylaxis.

Q2: What is the CAS number?

A: 723-46-6.

Q3: How does sulfamethoxazole work?

A: It competitively inhibits dihydropteroate synthase (DHPS), blocking PABA utilization and folic acid synthesis. With trimethoprim (DHFR inhibitor), it creates a sequential folate pathway blockade with bactericidal synergy.

Q4: What is co-trimoxazole?

A: The fixed combination of sulfamethoxazole and trimethoprim in a 5:1 ratio (e.g., 400 mg/80 mg or 800 mg/160 mg), which is bactericidal and listed as a WHO Essential Medicine.

Q5: What is sulfamethoxazole used for?

A: Urinary tract infections, respiratory infections, traveler's diarrhea, and - as co-trimoxazole - Pneumocystis jirovecii pneumonia prophylaxis/treatment, toxoplasmosis and nocardiosis. In veterinary: canine/feline UTI, skin and respiratory infections.

Q6: What documents are provided with each batch?

A: Batch-specific COA, HPLC report, IR identity records, melting point data, MSDS/SDS and relevant export documentation.

Q7: What purity do you supply?

A: Standard ≥98% HPLC; typical batch result 99%. USP/EP-grade available on request.

Q8: Where can I buy it from China?

A: HDM BIO supplies bulk Sulfamethoxazole Powder with batch COA and global export support.

Q9: How much does Sulfamethoxazole Powder cost?

A: Bulk pricing depends on synthesis costs, purity/grade, regulatory compliance, order volume and logistics. Contact HDM BIO for a current quotation.

Q10: Are there any safety concerns?

A: Sulfamethoxazole can cause hypersensitivity reactions including life-threatening Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), crystalluria/renal injury, hematologic effects and hyperkalemia. Hemolysis may occur in G6PD deficiency. Use with adequate hydration and medical supervision. Not for direct clinical administration.